Treatment of textiles with cross-linkable acrylic polymers and the resulting products



United States Patent ABSTRACT OF THE DISCLOSURE A. process for treatingsheer knit or woven textile articles. to improve their resistance topulling, snagging and picking comprising applying an equeous acrylicpolymeric emulsion containing ester groups to a textile article, dryingthetreated textile article to partially cross-link the polymer, andcuring theacrylic polymer ,under textile resin curing conditions so asto cross-link the polymer an'd to obtain a soft, resilient coating onthe textile article.

This invention relates to a process and resulting article wherein atextile material is treated with a polymeric emulsion to increase thematerials resistance to pulling, snagging and picking.

In the production of knitting or weaving of sheer garments such as sheerknitted stockings some difliculties arise that are peculiar to the art.Due to the deviation of production elements such as sinkers and needlesin knitting machines, stitch formation of an irregular type will resultin articles that will run, snag or pull when worn.

Various suggestions have been made in the prior art to solve theseproblems and various types of articles'including stockings are offeredon the market which are resistant to the aforesaid difficulties by theadoption of other than plain knit structure, for example, through theuse of tuck stitches or draw stitches involving the knitting ofdifferent parts of a textile article of two different yarns. In such anarticle resistance to pulling snagging and picking may be accomplishedby use of one plain knit stitch and another special stich may beproduced. T o the greater majority of wearers these textile articles areunacceptable for general use because of the appearance of the garmentsf,a,

Chemical and adhesive treatments have been utilized in the prior art toovercome the difficulties of pulling, snagging and picking in woven andknitted fine dinier sheer garments. None of these treatments have beenreally comcercially successful because any'treatment that is proven tobe effective will affect the hand and/or the stretch characteristics ofthe garments.

On object of the present invention is to provide textile articlesincluding sheer stockings which have exceptional resistance to picking,running or snagging, while demonstrating excellent hand and stretchcharacteristics.

It is also an object of this invention to develop a finish for ladieshose that will significantly reduce the tendency to snag,'pick and pullwherein the finish can be applied by a hosiery finisher in a simple andpractical manner.

According to the present invention a process is pro vided for treating atextile article with an aqueous liquid wherein the liquid contains apolymeric substance comprised of at least some acrylic monomers, some ofwhich are esters.

' The polymers and copolymers that are useful in this invention arethose acrylic emulsion polymers that crosslinkor cure to form arelatively soft film. These polymers should combine softness, resilienceand low temperature flexibility with improved dry cleaning fastness andexcellent wash fastness. These polymers should be cross-- 3,476,581Patented Nov. 4, 1969 linkable which means that should either be selfcrosslinking or possible of reacting or curing in situ with anitrogeneous or other type of external cross-linking agent, under thecuring conditions of this invention set forth hereinafter. The compoundor compounds having groups that are capable of cross-linking may bereacted in situ with the acrylic monomer during the curing step of thisprocedure if desired, to form a thermosetting type resin.

The process of the present invention may be applied to knitted or wovenfabrics or articles and is applicable to wool or nylon or mixtures ofthese materials, and also to fabrics or articles containing wool and/ornylon in admixture with other fibers such as the synthetic protienfibers, e'.g., material known under the name Ardil and the ethyleneglycol terephthalic polyesters, e.g., material known under the nameTerylene, cotton, rayon, casein fiber, cellulose acetate, e.g., theviscose rayon material known under the name Fibro. I Among the articleswhich may be treated according to the present invention are underwear,or outerwear garments, hose, half-hose, quarter-hose, three-quarterhose, socks and stockings, felts, hats, ties, furnishing fabrics,upholstery for motor cars, gloves, scarves, curtains, etc.

The process of the invention may be applied to a dyed or undyedmaterial. In the case of the undyed material the dyeing may be effectedduring the process of the present invention or may be effectedsubsequent to this treatment. It is, however, preferable that thetextile materials treated in accordance with this invention should befree of other finishes, i.e. lanolin or the like.

The fabrics or articles treated in accordance with this invention shownan increased resistance to picking, snagging or pulling.

The term picking as used herein refers to the tendency of sheer fabricsto have unsightly broken threads and holes, this characteristicparticularly being present in knitted stockings and the like. Themeasurement of this physical characteristic of fabrics particularlystockings can be carried out on the Hanes Pick Tester, U.S. Patent3,044,293. This tester comprises a small cylindrical tumbling deviceequipped with baffies and with a number of straight pins protruding fromthe cylinder Wall. In the use of this pick testing device the stockingsare first board inspected and all defects marked and then put into thepick tester and tumbled for three minutes at approximately 18.8 r.p.m.The straight pins hold the hose as well as" the bafiies in the tumblerthus giving hose a tumbling action. After three minutes in the testerthe samples are removed and inspected for defects. Defects areclassified as'to their location in the hose (boot or welt). Theadditional defect totals are recorded.

.The process of this invention is particularly beneficial in treatinggarments or fabrics produced from textured textile yarn. One of thetextured yarns that is particularly difficult to work with and has beenproven to give a relatively high numberof picks, pulls and snags inwoven or sheer knitted garments is AGILON yarn or any equivalentedgecrimped yarn. AGILON yarns as produced in accordance with the methodand apparatus as set forth in U.S. Patent 2,919,534 to Bolinger et al.or by the apparatus set forth in Patent No. 2,977,746 to Klein,particularly shows improved results when finished in accordance with theprocess of this invention. It is known that AGILON stockings,particularly those knitted from multifilament yarn, i.e., 15 denier, 3filament willdemonstrate between 10 and 20 picks per hose when tested onthe Hanes pick tester described above. After treatment according to theprocess of this invention, the AGILON stockings will generally whentested on a Hanes pick tester demonstrate from one to five picks perhose, under the same conditions.

Garments made from yarn produced from other texi 3 turing methods suchas the Pinlon process, covered in part by Patents 2,914,810, 3,153,272and 3,174,206 will show marked improvement when finished in accordancewith the process of this invention.

Yarns made by other texturing processes such as Spunize or by other gearcrimping, stulfer box or false twist crimping methods can be treatedbeneficially in ac cordance with this invention and will improve thepick, pull and snag resistance of the garments that are so treated.

The polymers that are most useful in this invention are those known tothe art as the acrylics, including particularly the acrylates. Thesepolymers may be homopolymers or copolymers so long as the acrylate chainhas both ester groups and groups that are capable of cross-linking withthe polymeric chain under properly catalyzed conditions. It is, however,preferred that copolymers be utilized for the most part. In general, thepolymers utilized in this invention will have molecular weights rangingfrom about a few hundred, i.e. three hundred to about three million andbe comprised from an acrylic monomer having ester groups and a sidechain group that is comprised of compounds selected from the grouphaving epoxide, carboxyl and/ or methylol groups. Among the mostpreferred polymers are the acrylates and particularly the alkyl acrylatemonomers such as methylacrylate, eahylacrylate, propylacrylate,butylacrylate, pentylacrylate and the like up to and including 12 carbonatoms alkyl acrylates. Within this particular group poly-n-butylacrylatehaving a molecular Weight in the range of one thousand to one million isthe preferred species.

Any of the above acrylic monomers may be reacted with anycopolymerizable compounds containing epoxide groups, carboxyl groups ormethylol groups. Compounds having functional groups that can becross-linked are preferably n-methylolacrylamide, glycidyl acrylate,acrylic acid and methacrylic acid. These co-monomers that can react inthe copolymerization process or in situ to form a side chain grouphaving an epoxy, carboxy and/or methylol group are usually present in anamount ranging from 0.5 percent to percent by weight of the polymericmaterial formed.

In addition to the above compounds that have functional groups that canbe cross-linked, particularly where the crosslinking takes place in anin situ reaction, acrylic anhydride, glycol esters of acrylic ormethacrylic acid and acrylamide may be used.

The backgone of the polymeric chain may be comprised of any of theacrylic monomers set out in the book entitled Reaction Of The AcrylicEsters, reprinted from Chapter VI Monomeric Acrylic Esters by E. H.Riddle, published by the Reinhold Publishing Corporation, 430 ParkAvenue, New York (Sp-182 copyright 1954 by the Reinhold PublishingCorporation).

The polymerization or copolymerization of these acrylic monomers may becarried out with either a persulfate or peroxide catalyst or with aredox catalyst system in accordance with the recipes and formulationsset forth in the publication entitled Emulsion Polymerization OfMonomeric Acrylic Esters, published by Rohm and Haas Company, SpecialProducts, Washington Square, Philadelphia 5, Pennsylvania (Spl54Published in April 1960, superseding Sp-l54 dated May 1959). In thesepolymerization and copolymerization reactions which are generallywell-known in the prior art the cross-linkable monomer should be presentin the emulsion reaction in the general range of 0.2% to by Weight, ofthe acrylic monomer.

Among the preferred cross-linkable compounds characterized above are themethylol acrylamides, e.g.z

(N-methylol-methacrylamide) H0oH2NoH3( iCH=oH(N-methylol-N-methylaerylarnide) i HOCHCH3-NHCCH=CHz(N-methylmethylolacrylamide) and Ii CCH=CH2 HOGHzN Additional suitablemethylol acrylamides include those having more than one methylol group,such as shown in the following formulae:

R O-OHR wherein R is selected from hydrogen, lower alkyl and the residueof an aldehyde; R is selected from hydrogen and methyl; R is selectedfrom hydrogen and lower alkyl; and X is selected from oxygen and sulfur.

Other acrylamide compounds may be utilized, e.g.,alkylene-bisacrylamides to provide compounds of the following formulae:

(VII) CHR'OR wherein R R, R and X are as before, and x: 1,6 e.g.,N-methylol-methylene-bis (acrylamide), methylene-bis- (N-methylolacrylamide) and the like.

Additional, but less preferred, compounds include:

Rfi-C-Hl-N-OHROR R -CC-NOI-IR OR wherein R R R and X are as given above,e.g., as wherein R and R are hydrogen and X is oxygen.

Tse catalysts useful in activating the acid or base reactive groups arethose conventionally used to activate the reaction of textile resins.Preferably, latent acid or base acting catalysts are utilized, that is,compounds which are acidic or basic in character under the curingconditions. The most common acid acting catalysts are the organic acids,metal salts, for example, magnesium chloride, zinc nitrate and zincfluoroborate and the amino salts, for example, monoethyanolaminehydrochloride and 2-amino-2-methyl-propanol nitrate.

The 'latent base acting catalyst utilized herein preferably comprisesalkali-metal salts, such as alkali-metal carbonates like sodiumcarbonate which is neutral to moldly alkaline, for example pH of about8.5 on the reaction under normal temperature conditions.

If fabrics containing a base reactive group are maintained at pH levelsabove about ten, however, degradation occurs, so that essentiallyneutral or mildly alkaline catalysts are preferred when base reactivecompounds are utilized.

Additional base acting catalysts include potassium bicarbonate,potassium carbonate, sodium silicate, alkali metal phosphates, such assodium or potassium phosphates, barium carbonate, quaternary ammoniumhydroxides and carbonates, for example, lauryl trimethyl ammoniumhydroxides and carbonates and the like.

The amount of catalyst to be utilized is that conventionally used inactivating the reaction between textile resins or polymers and hydroxygroups of cellulose, for example, up to about 5% by weight of an acidacting compound on the fabric with the preferred range being from about1% to about 2%, based on the weight of the polymer. A preferred rangefor the base acting catalyst is again the conventional amount and isgenerally between about 0.2% to about 16%, preferably about 2 to 16%.

The amount of catalyst to be utilized will depend in part on thetemperature at which the reaction is conducted and the amount ofcatalyst consumed in the reaction. For example, when base catalysts areutilized and if a highly acidic group is released during the reaction,the amount of base applied to the textile material should be at leastsufiicient to provide an excess of base in addition to that which isconsumed by the highly acidic group.

The polymeric material described above is utilized in a water baseemulsion as the treatment medium for sheer fabrics and garments inaccordance with this invention. In order to carry out the processes ofthis invention the polymeric material is first diluted in an aqueousemulsion. The polymer may be present in an amount ringing from about0.1% to 46% solids by weight, based upon the Weight of the aqueousemulsion. In the preferred embodiment of this invention the polymericrnaterial is primarily insoluble in water and will preferably be presentin the emulsion in the approximate range of 0.3 to 28% solids, byweight, based upon the weight of the emulsion. Where a viscosityimprover can be utilized to obtain a more uniform emulsion a highersolid content can be used.

In order to effect cross-linking of the polymer and in order toaccomplish good adhesion to the fabric or garment substrate it isnecessary to add a catalytic initiator to the aqueous emulsion for thereaction. These catalytic intiators are preferably acid catalysts thatare well-known in the textile arts, although in certain instances anddepending upon the polymers or copolymers selected, a basic catalyst maybe used. Among the catalysts most frequently used are oxalic acid anddiammonium phoshate.

p It should be understood that any of the Well-known lubricants that areconventionally used to facilitate subsequent processing of fabrics orstocking may be added to the polymeric emulsions so long as they arecompatible therewith, i.e. Lanogel 41 Likewise, antifoaming agents andother additives that do not aifect the hand, stretch or other desirablecharacteristics of the fabric or garment may be added to the emulsion.

After the desired emulsion has been prepared and brought to the properconsistency either by the dilution of a polymeric material that may be apowder or granular or by the addition of the polymeric material to waterto form an aqueous emulsion and after the catalyst has been added in aproper concentration usually ranging from 0.1% to 20%, by weight, basedupon the weight of the emulsion, the process if treating the garments orfabrics is commenced.

In the usual procedure the aqueous emulsion is applied to the fabric orgarment. For example, a number of stockings or other sheer fabrics orgarments may be placed in a suitable container that is designed for aliquid treatment of this nature, and the articles or garments dipped andpreferably submerged in the emulsion bath for a period of time rangingfrom a few seconds to five minutes or more. The emulsion bath may be atroom temperature or at a temperature ranging from about 50 F. to F.After the textile article has been subjected to this treatment for arequired length of time the article is placed in an extractor for thepurpose of extracting the excess liquid emulsion that may remaintherein. This extractor may comprise a spin dryer, for example. Itshould be understood that other means for applying the emulsion for thisinvention may be utilized, for example, spraying, vapor treatment or thelike. Subsequent to extraction the garments are preferably air dried fora period of time ranging approximately from an hour to 24 hours. At theend of this period the polymeric materal will usually be present on thegarment or fabric in a weight percentage varying from about 0.1 to 10%,based on the Weight of the garment or fabric. During this period of timedue to the catalytic initiator present in the emulsion, some curing orcross-linking will take place. It is preferable, though not absolutelynecessary, that some curing take place in this stage so that subsequenttreatments of the garments or fabric may be facilitated, withoutadhesion of the garments or fabrics to the processing equipment. Forexample, in the further processing of stockings which involves boardingif some curing is allowed at room temperature prior to curing in asubsequent step at higher temperature boarding may be accomplished muchmore quickly and with less difiiculty than otherwise.

Where stockings are processed according to this invention a number ofalternative boarding procedures may be used. In this first procedure tobe described the stockings may be boarded while wet. Here a lightcoating of oil or equivalent are placed on the boards with a subsequentremoval of any excess oil. The boards are then preheated to varyingtemperatures in the range of approximately 200 to 300 F., mostpreferably 240 to 260 F. Heating of the boards may be accomplished as inconventional boarding processes i.e., by use of steam. The hose are thenplaced on the bot boards and are allowed to remain on the boards untilall welts are dry. The period of time involved in this boardingprocedure will vary from approximately one to five minutes. The hose arethen preferably vacuumed for a few seconds and the dry hose removed fromthe boards.

In an alternative procedure and the one which is preferred for use inaccordance with this invention garments, including hose are allowed todry after treatment with the above described emulsion and extractionfora sufficient period of time to effect the partial cure of thispolymeric material. In this procedure the boards are coated with a lightoil such as knitting oil. In any respect, such oil is removed. The hoseare then placed on hot boards and allowed to remain there for a periodranging from one to five minutes at the above temperatures. Again, thedry hose are vacuumed for a few seconds and removed from the boards.

A typical procedure for the preparation of the polymers of the type thatare useful in this invention is as follows:

To a 1000 ml. round bottom five-neck flask equipped with a thermometer,a stirrer (a) with a half moon paddle, a water cooled condenser and fourmore openings, the addition of the chemicals listed below is started.

7 At first 75% of the water and of the emulsifiers and all of the sodiumbicarmonate are introduced in the flask (this is the initial charge);the rest of the chemicals, except the oxidizing agent, ammoniumpersulfate and the reducing agent Formopon are used to form a preemulnotspecifically described herein but further within the scope and spirit ofthe invention.

EXAMPLE Thirty-six grams of an n-butyl acrylate with self crosssion. Thepreemulsion must be stable in order to assure linking methylol groups ofthe type prepared above (46% uniform and consistent addition of thechemicals. This olid a ix d with one gallon of water. One dozen is doney Obtaining the maximum i c sity of the emulladies hose were put into acotton dye bag and submerged siOIl system 11P0I1 slOW addition of theaefyletes t0 the in the emulsion and agitated for five minutes. Thedozen water phase, Where the emulsifiers were already dis- 1O hose inthe cotton dye bag were removed and extracted solved, and With 810Wstirring, an Oil in Water stable for one minute, then air dried at roomtemperature for a preemulsion is The speed of the stiffer Was few hours.Hose were cured by boarding at 255 F. for 110416 -P- until about thelast -15 of the p one and one-half minutes. Hanes pick test results on36 emulsion at Which Point the Speed Was increased to 125 tests gave anaverage value of 3.41 picks per hose, which -P- of this preemulsion 25%is added to the Ieae' is a three to four times improvement over currentcomt on fl k ft e initial Charge is spafged With nitrogen mercialfinishes. The pick test procedure used in this exfor one hour andforty-five minutes at the raite of ca. 60 ample i as fgllow bubbles perminute. One hour and fortyve minutes later the reducing agent is added,followed by the addi- (1) code or number each hose qg a k h tion of68.3% of the oxidizing agent (ammonium per- (2) .Pull h hose over boardanfil elm y.each pm at sulfate) five minutes later. At this point thetemperature mlght i m the hose Use an Ink felt Pm for mar mg begins torise, the emulsion looks blue, and at 29 C. the these K addition of thebalance of the preemulsion is resumed, at (3 Enter (6) hose mm Plcktests on each cycle ca. 55-65 drops per minute. The reaction temperatureRun Plck tests for three (3) mmutes or a clock Setis kept 53:2" C. andmay be regulated to a great extmg of 14 on h F clock tent by the rate ofaddition of the preemulsion. When (5) machme 1S Stopped remove hose frommathe reaction temperature began to drop (even after an chme'bemgCareful not to further Snag the hose increase in preelumsion additionrate), then, the reaction hose board 1 f and recqrd temperature wasallowed to drop to C While the picks 1n hose. Identify each pick 1norder that it W11] rate of addition of the preemulsion was slowed downnot be counted agam' gradually. At this point 1 ml. of the oxidizingagent was (7) Run hose through tests for SIX (6) on porcedure added andthe temperature began to rise; this was folabove lowed by an increase ofthe rate of addition of the pre- (8) At end of SIX (6) i total all picksPer stockmg emulsion to about 65 drops per minute. As the viscosity andget an ,average of plcks per hose Record results on of the reactionincreased the rate of stirring was informs Provlded' creased, so as tomaintain a slight Vertex in the p y Having thus described the inventionwhat is claimed is: erization reaction. While the exotherm was beingdis- 1, Th th d f treating a stocking comprising apply- P again the sameprocedure Was used, that ing an aqueous emulsion of a cross-linkablepolyacrylate ducing the rate addition of the preemulsion before theolymer to the stocking, drying the stocking to partially last portion ofthe oxidizing agent was added; the rate 40 cross-link the polymer,boarding the dried stocking in of addition was once mo e increa ed andthe e h rm the presence of steam and curing the partially cross-linkedwas suflicient to complete the preemulsion addition. Ten polymer to a,cross-linked condition by heating to obtain minutes after all thepreemulsion was added the temperaa stocking with a soft cross-linkedpolyacrylate coating, ture reached the maximum of 54 C. At this point asaid cross-linkable polymer having a cross-linkable memslight drop intemperature was observed (53.7 (3.), her selected from the groupconsisting of methylol, carvacuum was applied for thiry minutes. Thisbrought the boxy and epoxy groups. temperature down to The reaction wasstopped 2. The method of claim 1 wherein the polymer is polyand h amountof eoaguhlm Was estimated be n-butylacrylate (having a cross-linkagemember selected gm. Upon dilution and stirring no cobweb formation wasfrom the group consisting of methylol, carboxy and epoxy observed. Afilm made from this polymer was practically groups). clear (with veryfew and small ripples) and extremely 3. The method of claim 2 whereinthe stocking is boardsoft and slightly tacky. ed at a temperature in therange of 240 to 260 F. (in the The chemicals used in this preparationare as follows: presence of steam).

Weight or Chemicals Used Synonym Volume 1 H2O Water 158.5 gms. 2 TritonX-405 8.70 gms. 3 CHz(CHz)COOSO3Na(29%) Sodium Lauryl Sulfate (Sipex UB)5.90 gms. 4 NaHCO; Sodium bicarbonate. 0.10 gms.

6 CH2C(CH )C0OCH Methyl methacrylate. 73 gms 7 CHaCHaCI-IzCHCOOCeHsButyl acrylate 118.61 gms 8 CHQCXOHQCOOH Methacrylic acid... 1 34 gms 9NaHSOzCHzOZHzO Formopon 2.93 ml.

10 (NIL)2S2Os(5%) Ammonium pcrsulfate 5.86 ml.

A typical polymer of th1s type is now made by the 70 Rohm and Haas, Co.under the name E-287.

The following example is illustrative of the concept of invention and isnot to be considered as limiting thereof. Further, it should beunderstood that those persons skilled in the textile art will be ablefrom a study of this specification to make many variations andmodifications 4. The method of claim 3 wherein the cross-linkable memberis N-methylol-acrylamide.

5. A nylon stocking treated according to the process of claim 1.

6. The stocking of claim 5 wherein the yarn comprising the stocking isproduced from textured yarn.

by an edge-crimping process.

UNITED STATES PATENTS Adelman 117-140 Collins et a1. 117-138.8 Baechtold117-1388 Kuppers 117138.8 X

5 WILLIAM D. MARTIN, Primary Examiner fi g fi l :l: :?g:;i T. G. DAVIS,Assistant Examiner Gottschalck 2-239 Bolinger et a1. 5734 Hurwitz117-461 X 10 117-138.8, 139.5, 161

